I have a little story that may shock some of you. Years ago I was a tech at a Chevy dealer. While there, I went to a class at the Warren Technical Center, near Detroit, on the then new 6.2L Diesel engine. We discussed fuel gelling at cold temperatures and were told by the instructor that it was perfectly safe, acceptable and recommended to add gasoline to the diesel at a 1 to 10 ratio. In fact, he said that it would not hurt anything to go as high as 1 to 4 on the mix in extremely cold weather. I had never heard of this before so I was skeptical. The instructor assured me that it was OK and that there was enough lubrication in the diesel fuel so that no harm would be done to the injection pump and the gasoline would not damage the engine itself. Since he was a genuine GM instructor at the GM factory school I decided he must know what he is talking about. During the following winter I had the opportunity to try it myself. My service manager asked me to take a customer's new Chevy K2500 w/6.2L pickup home for the weekend to try and diagnose an odd driveline vibration. That Sunday morning it was 22 below zero which is extremely cold for southern Michigan. I needed to make a trip to the store so I took the truck. I had plugged the block heater in over night for just such an occasion as I knew it was going to get cold. The truck started right up. I let it warm up for a few minutes so I would have some heat and took off. The store was about 3 miles away. The first two miles were fine and then it started to lose power. I thought it may be fuel gelling so I switched to the other one of the dual tanks. It recovered and ran OK until I was almost to the retail part of town. As it started to die again I remembered what I had learned the summer before about adding gas to the diesel fuel. I quickly spotted a gas station and almost made it, stopping about 20 feet short of the pumps. No problem, I thought, I'll just go in and borrow a can, put some gas in it and then pour it into the truck. Wrong. The station did not have a can to lend so there I was, 20 feet away from salvation. There was a K Mart about a block away so I walked over to it in the -22 degree weather with the wind blowing and bought a 1 gallon can. I went back to the station, bought 1 gallon of gas and poured it into the tank that was about half full. I then pushed on the side of the truck to get it rocking so the gas would mix with the diesel and hopefully melt the wax (so called gelling is actually the parafin wax that is in all oil. At cold enough temperatures it turns into little globs of clear wax that plugs things up and stops the flow of fuel) that had collected on the filter sock on the pickup tube in the tank. It worked. The truck started and I was able to drive back home with no more problems. (Later versions of the 6.2L engine had fuel line heaters near the engine and no filter socks in the tank.) It made a believer out of me. In the 23 years since and having driven diesels most of those years year around in Michigan I have never had a fuel gelling problem. I think the additives that are available today for diesel fuel are a much better solution for fuel gelling but in a pinch, I would not hesitate to use gasoline again. It kept me from a long cold walk home.
